Time & Date
Age Calculator
Work out a person's exact age in years, months, and days from a date of birth.
The result gives completed years first, then completed months, then remaining days, so it is the exact age on the chosen date.
Formula
Age is found by borrowing months and days, just like manual subtraction: if the day or month has not been reached yet in the current year, borrow from the month or year above.
How it works
Enter the date of birth and the date you want the age on. The calculator counts completed years first, then completed months, then remaining days, so a birthday that has not happened yet this year is not counted as a full year.
Worked example
For example, a date of birth of 2000-05-15 measured on 2026-10-28 gives an age of 26 years, 5 months, and 13 days.
FAQs
Why is the age sometimes one year less than the year difference?
Because only completed years count. If this year's birthday has not arrived yet, that year is not complete.
Does it work for leap-day birthdays?
Yes, with the usual convention: in non-leap years the birthday is treated as falling in late February for the borrowing calculation.
Can I use it for a future date?
Yes. Pick any later reference date to see the age on that date.
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